A lighting unit in which various light sources used in electronic equipment are utilized has been implemented in such a manner as to increase light efficiency by utilizing an appropriate light source for each property of the electronic equipment.
Even though a lighting unit, which has been recently used in electronic equipment, is a backlight unit applied to a flat display, the lighting unit may be variously applied to an indoor lamp, or a headlamp, a fog lamp, a backward light, a sidelight, a license plate light, a taillight, a turn signal lamp, a hazard flasher lamp installed at the outside of a vehicle, or an indoor lighting lamp installed at the inside of a vehicle.
However, the most of lighting is mainly realized by a method of increasing luminance of a surface light source by applying a member such as a light guide plate for enabling the efficient transmission of light.
For example, FIG. 1 roughly illustrates a structure of a convention lighting unit used in a vehicle.
As illustrated in FIG. 1, a conventional light guide for a vehicle includes: a light source 10 emitting light at a certain fixed emitting angle; and a total reflection part 20 adopted to fully reflect light emitted from the light source 10, wherein the total reflection part 20 generally has a case form with an internal space, and is configured so that a first total reflection surface 21 and a second total reflection surface 22 can be formed, and as illustrated in FIG. 1, dispersion points 30 for dispersing light are formed inside the total reflection part 20 so that the light passing through the total reflection part 20 can be dispersed by the dispersion points, and can be then emitted to the outside. That is, the light incident from the light source 10 to the total reflection part 20 travels along the total reflection part 20 through a process of being reflected by the first and second total reflection surfaces 21, 22 of the total reflection part 20, and the light is dispersed by the dispersion points 30 and is emitted to a direction to perpendicular to a traveling direction. However, since the conventional light guide for a vehicle is mounted to a rear lamp of a vehicle body in a general form, it is problematic in that there is a limit in selecting a vehicle based on a design in terms of buyers in a state of aesthetic impression being reduced.
In order to overcome this limit, as shown in (B) of FIG. 1, the structure of a lighting unit for a vehicle including: a bezel 1 formed in a housing form in a rear lamp of a vehicle; a light source 2 inserted into the bezel 1 and emitting light; a light guide panel 3 adopted to guide light emitted from the light source 2, and having one side into which printed patterns 3-1 are inserted, namely, the structure for increasing a design effect by providing the printed patterns inside the lighting unit, has been suggested. However, such a structure is problematic in that since the printed patterns 3-1 are used, light extraction efficiency is reduced, and reliability of a printing ink is also reduced. Also, the structure has a limit in satisfying luminous intensity and light distribution because the light source is inserted into merely one side.